The invention relates generally to a method for applying energy to shrink a hollow anatomical structure, such as a fallopian tube or a vein, including, but not limited to, superficial and perforator veins, hemorrhoids, and esophageal varices, and more particularly, to a method using an electrode device having multiple leads for applying radio frequency (RF) energy, microwave energy, or thermal energy.
The human venous system of the lower limbs consists essentially of the superficial venous system and the deep venous system with perforating veins connecting the two systems. The superficial system includes the long or great saphenous vein and the short saphenous vein. The deep venous system includes the anterior and posterior tibial veins which unite to form the popliteal vein, which in turn becomes the femoral vein when joined by the short saphenous vein.
The venous system contains numerous one-way valves for directing blood flow back to the heart. Venous valves are usually bicuspid valves, with each cusp forming a sack or reservoir for blood which, under retrograde blood pressure, forces the free surfaces of the cusps together to prevent retrograde flow of the blood and allows only antegrade blood flow to the heart. When an incompetent valve is in the flow path, the valve is unable to close because the cusps do not form a proper seal and retrograde flow of the blood cannot be stopped. When a venous valve fails, increased strain and pressure occur within the lower venous sections and overlying tissues, sometimes leading to additional valvular failure. Two venous conditions which often result from valve failure are varicose veins and more symptomatic chronic venous insufficiency.
The varicose vein condition includes dilation and tortuosity of the superficial veins of the lower limbs, resulting in unsightly discoloration, pain, swelling, and possibly ulceration. Varicose veins often involve incompetence of one or more venous valves, which allow reflux of blood within the superficial system. This can also worsen deep venous reflux and perforator reflux. Current treatments of vein insufficiency include surgical procedures such as vein stripping, ligation, and occasionally, vein-segment transplant.
Chronic venous insufficiency involves an aggravated condition of varicose veins which may be caused by degenerative weakness in the vein valve segment, or by hydrodynamic forces acting on the tissues of the body, such as the legs, ankles, and feet. As the valves in the veins fail, the hydrostatic pressure increases on the next venous valves down, causing those veins to dilate. As this continues, more venous valves will eventually fail. As they fail, the effective height of the column of blood above the feet and ankles grows, and the weight and hydrostatic pressure exerted on the tissues of the ankle and foot increases. When the weight of that column reaches a critical point as a result of the valve failures, ulcerations of the ankle begin to form, which start deep and eventually come to the surface. These ulcerations do not heal easily because of poor venous circulation due to valvular incompetence in the deep venous system and other vein systems.
Other related venous conditions include dilated hemorrhoids and esophageal twisted veins. Pressure and dilation of the hemorrhoid venous plexus may cause internal hemorrhoids to dilate and/or prolapse and be forced through the anal opening. If a hemorrhoid remains prolapsed, considerable discomfort, including itching and bleeding, may result. The venous return from these prolapsed hemorrhoids becomes obstructed by the anal sphincters, which gives rise to a strangulated hemorrhoid. Thromboses result where the blood within the prolapsed vein becomes clotted. This extremely painful condition can cause edema and inflammation.
Varicose veins called esophageal varices can form in the venous system with submucosa of the lower esophagus, and bleeding can occur from the dilated veins. Bleeding or hemorrhaging may result from esophageal varices, which can be difficult to stop and, if untreated, could develop into a life threatening condition. Such varices erode easily, and lead to a massive gastrointestinal hemorrhage.
Ligation of a fallopian tube (tubal ligation) for sterilization or other purposes is typically performed by laparoscopy. A doctor severs the fallopian tube or tubes and ties the ends. External cauterization or clamps may also be used. General or regional anesthetic must be used. All of the above are performed from outside the fallopian tube.
Hemorrhoids and esophageal varices may be alleviated by intra-luminal ligation. As used herein, xe2x80x9cligationxe2x80x9d or xe2x80x9cintra-luminal ligationxe2x80x9d comprises the occlusion, collapse, or closure of a lumen or hollow anatomical structure by the application of electrical energy from within the lumen or structure. As used herein, xe2x80x9cligationxe2x80x9d or xe2x80x9cintra-luminal ligationxe2x80x9d includes electro-ligation. In the case of fallopian tube ligation, it would be desirable to perform the ligation from within the fallopian tube itself (intra-fallopian tube) to avoid the trauma associated with external methods.
Ligation involves the cauterization or coagulation of a lumen using energy, such as that applied through an electrode device. An electrode device is introduced into the lumen and positioned so that it contacts the lumen wall. Once properly positioned, RF energy is applied to the wall by the electrode device thereby causing the lumen to shrink in cross-sectional diameter. In the case of a vein, a reduction in cross-sectional diameter of the vein, for example from 5 mm (0.2 in) to 1 mm (0.04 in), significantly reduces the flow of blood through a lumen and results in an effective occlusion. Although not required for effective occlusion or ligation, the vein wall may completely collapse thereby resulting in a full-lumen obstruction that blocks the flow of blood through the vein. Likewise, a fallopian tube may collapse sufficient to effect a sterilization of the patient.
One apparatus for performing ligation includes a tubular shaft having an electrode device attached at the distal tip. Running through the shaft, from the distal end to the proximal end, are electrical leads. At the proximal end of the shaft, the leads terminate at an electrical connector, while at the distal end of the shaft the leads are connected to the electrode device. The electrical connector provides the interface between the leads and a power source, typically an RF generator. The RF generator operates under the guidance of a control device, usually a microprocessor.
The ligation apparatus may be operated in either a monopolar or bipolar configuration. In the monopolar configuration, the electrode device consists of an electrode that is either positively or negatively charged. A return path for the current passing through the electrode is provided externally from the body, as for example by placing the patient in physical contact with a large low-impedance pad. The current flows from the ligation device through the patient to the low impedance pad. In a bipolar configuration, the electrode device consists of a pair of oppositely charged electrodes of approximately equal size, separated from each other, such as by a dielectric material or by a spatial relationship. Accordingly, in the bipolar mode, the return path for current is provided by an electrode or electrodes of the electrode device itself. The current flows from one electrode, through the tissue, and returns by way of the oppositely charged electrode.
To protect against tissue damage; i.e., charring, due to cauterization caused by overheating, a temperature sensing device is attached to the electrode device. The temperature sensing device may be a thermocouple that monitors the temperature of the venous tissue. The thermocouple interfaces with the RF generator and the controller through the shaft and provides electrical signals to the controller which monitors the temperature and adjusts the energy applied to the tissue through the electrode device accordingly.
The overall effectiveness of an ligation apparatus is largely dependent on the electrode device contained within the apparatus. Monopolar and bipolar electrode devices that comprise solid devices having a fixed shape and size can limit the effectiveness of the ligating apparatus for several reasons. Firstly, a fixed-size electrode device typically contacts the vein wall at only one point on the circumference or inner diameter of the vein wall. As a result, the application of RF energy is highly concentrated within the contacting venous tissue, while the flow of RF current through the remainder of the venous tissue is disproportionately weak. Accordingly, the regions of the vein wall near the point of contact collapse at a faster rate then other regions of the vein wall, resulting in non-uniform shrinkage of the vein lumen which can result in inadequacy of the overall strength of the occlusion and the lumen may eventually reopen. To avoid an inadequate occlusion, RF energy must be applied for an extended period of time so that the current flows through the tissue generating thermal energy including through the tissue not in contact with the electrode to cause that tissue to shrink sufficiently also. Extended applications of energy have a greater possibility of increasing the temperature of the blood to an unacceptable level and may result in a significant amount of heat-induced coagulum forming on the electrode and in the vein which is not desirable. This can be prevented by exsanguination of the vein prior to the treatment, and through the use of temperature regulated power delivery.
Secondly, the effectiveness of a ligating apparatus having a fixed-size electrode device is limited to certain sized veins. An attempt to ligate a vein having a diameter that is substantially greater than the electrode device can result in not only non-uniform heating of the vein wall as just described, but also insufficient shrinkage of the vein diameter. The greater the diameter of the vein relative to the diameter of the electrode device, the weaker the energy applied to the vein wall at points distant from the point of electrode contact. Accordingly the vein wall is likely to not completely collapse prior to the venous tissue becoming over cauterized at the point of electrode contact. While coagulation as such may initially occlude the vein, such occlusion may only be temporary in that the coagulated blood may eventually dissolve recanalizing the vein. One solution for this inadequacy is an apparatus having interchangeable electrode devices with various diameters. Another solution would be to have a set of catheters having different sizes so that one with the correct size for the diameter of the target vein will be at hand when needed. Such solutions, however, are both economically inefficient and can be tedious to use. It would be desirable to have a single catheter device that is usable with a large range of sizes of lumina.
Although described above in terms of a vein, the concepts are generally applicable to other hollow anatomical structures in the body as well. For consideration of avoiding unnecessary repetition, the above description has been generally confined to veins.
Hence those skilled in the art have recognized a need for a method capable of more evenly distributing RF energy along a circumferential band of a wall of the target anatomical structure where the wall is greater in diameter than the electrode device, and thereby provide more predictable and effective occlusion of anatomical structures while minimizing the formation of heat-induced coagulum. Such method should be applicable to the ligation of all the veins in the body, including but not limited to perforator and superficial veins, as well as hemorrhoids, esophageal varices, and also fallopian tubes. The invention fulfills these needs and others.
Briefly, and in general terms, the present invention provides a method for applying energy along a generally circumferential band of the wall of a hollow anatomical structure, such as a fallopian tube, a hemorrhoid, or an esophageal varix. The application of energy in accordance with this method results in a more uniform and predictable shrinkage of the vein wall.
In one aspect, the invention comprises a method of applying energy to a hollow anatomical structure from within the structure. The method includes the step of introducing a catheter into the anatomical structure; the catheter having a working end and a plurality of leads, each lead having a distal end, and each lead being connected to a power source. The method also includes the step of expanding the leads outwardly through the distal orifice and expanding the leads until each electrode contacts the anatomical structure. The method further includes the step of applying energy to the anatomical structure from the distal end of the leads, until the anatomical structure collapses to an effective occlusion.
In further aspects, the invention is directed to a method of applying energy intraluminally to a fallopian tube from a power source, comprising the steps of introducing into the fallopian tube, hemorrhoid, or esophageal varix a catheter having a working end with a plurality of primary leads disposed at the working end, each primary lead having a distal end and being connected to the power source, expanding the primary leads outwardly from the working end of the catheter, wherein the distal ends of the primary leads move away from each other and into contact with the wall of the fallopian tube, hemorrhoid, or esophageal varix, and applying energy to the fallopian tube, hemorrhoid, or esophageal varix from the distal end of the primary leads to collapse the fallopian tube, hemorrhoid, or esophageal varix to effectively occlude the fallopian tube, hemorrhoid, or esophageal varix. In a further aspect, the step of expanding the primary leads comprises the step of expanding the primary leads such that the distal ends of the primary leads are spaced no more than five millimeters apart along the fallopian tube, hemorrhoid, or esophageal varix.
In more detailed aspects, the method further comprises the step of extending the primary leads through an orifice formed in the working end of the catheter and expanding the primary leads, wherein the distance between two mutually opposed expanded distal ends is greater than the diameter of the working end. In another aspect, the method comprises the step of moving an outer sleeve away from the primary leads such that the primary leads extend past an orifice of the outer sleeve at the working end of the catheter and expand outwardly.
In yet further aspects, the method further comprising the steps of maintaining separation between the primary leads at a selected location with an alignment device positioned inside an outer sheath of the catheter, and moving the outer sheath in relation to the alignment device to extend the primary leads out the orifice. Furthermore, the method further comprises the steps of attaching the primary leads to an inner sheath, maintaining separation between the primary leads at a selected location with an alignment device positioned inside an outer sheath of the catheter, and moving the outer sheath in relation to the inner sheath to extend the primary leads through the orifice.
In other more detailed aspect, the step of introducing a catheter having a plurality of primary leads into the fallopian tube, hemorrhoid, or esophageal varix comprises the step of introducing a plurality of primary leads that are mounted to the working end in a cantilever arrangement. The method further comprises the step of moving an outer sleeve away from the cantilevered primary leads such that the primary leads extend past an orifice of the outer sleeve at the working end of the catheter and expand outwardly.
In a further aspect, the method further comprises the step of moving the catheter in the fallopian tube, hemorrhoid, or esophageal varix while continuing to apply energy to the fallopian tube, hemorrhoid, or esophageal varix.
In a further detailed aspect, the method further comprises the step of mounting a secondary lead to the working end, the secondary lead having a distal end and having a length exceeding that of the primary leads, wherein the step of extending the plurality of primary leads further includes the step of extending the secondary lead through the distal orifice. In another aspect, the step of applying energy to the fallopian tube, hemorrhoid, or esophageal varix comprises the steps of controlling the power source so that adjacent primary leads are of opposite polarity while maintaining the secondary lead so that it is electrically neutral, switching the polarity of the primary leads so that they are all of the same polarity upon collapse of the fallopian tube, hemorrhoid, or esophageal varix around the primary leads, and controlling the power source so that the secondary lead is of opposite polarity relative to the primary leads upon performing the step of switching the polarity of the primary leads so that they are of the same polarity.
In further aspects, a bend is formed in each primary lead, the bend formed in the direction away from the other primary leads such that each primary lead tends to move outward away from the other primary leads in the step of expanding the primary leads away from each other. The steps of sensing the temperature at the distal end of a primary lead and controlling the application of power to the primary leads in response to the temperature sensed at the distal end may also be included.
In another aspect, the method includes the step of compressing the hollow anatomical structure, such as a vein or fallopian tube, to reduce the anatomical structure to a desired size, and for exsanguination, before and/or during the application of energy to occlude or ligate the structure.
In yet another aspect, the method includes the step of flushing the hollow anatomical structure with fluid before the step of applying energy.